From the Guidelines
Nail pitting is primarily caused by psoriasis, an autoimmune condition that affects approximately 50% of people with psoriasis, as well as other autoimmune conditions and disruptions in the nail matrix. The most common causes of nail pitting include:
- Psoriasis, which affects approximately 50% of people with psoriasis 1
- Other autoimmune conditions such as alopecia areata and eczema (atopic dermatitis)
- Fungal infections of the nail (onychomycosis), which can sometimes cause pitting, though they more commonly cause discoloration and thickening
- Trauma to the nail matrix from injuries or habits like picking at the cuticles, which can lead to temporary pitting
- Certain medications, particularly those used for chemotherapy, which may cause nail changes including pitting as a side effect
- Reactive arthritis (formerly known as Reiter's syndrome) and connective tissue disorders like lichen planus, which can also manifest with nail pitting
According to the 2019 American College of Rheumatology/National Psoriasis Foundation guideline for the treatment of psoriatic arthritis, nail lesions, including pitting and onycholysis, occur in ~80–90% of patients with PsA 1. The pits form when cells in the nail matrix are shed before they fully mature, creating small depressions as the nail grows out. Treatment depends on addressing the underlying cause, such as using topical corticosteroids or systemic medications for psoriasis or antifungal treatments for fungal infections.
In terms of morbidity, mortality, and quality of life, it is essential to address the underlying cause of nail pitting to improve outcomes. For example, in patients with psoriatic arthritis, early identification and treatment of the condition can improve long-term outcomes and reduce the risk of progressive joint damage and higher mortality 1. Similarly, treating fungal infections promptly can prevent further complications and improve quality of life.
Overall, the most effective approach to managing nail pitting is to identify and treat the underlying cause, taking into account the potential impact on morbidity, mortality, and quality of life.
From the Research
Causes of Nail Pitting (Onycholysis)
- Nail pitting is a common feature of alopecia areata (AA) and can cause significant cosmetic disfigurement and functional impairment 2, 3, 4
- The nail findings in AA are presumed to be due to the same lymphocytic infiltration seen in hair bulbs in individuals with AA 3
- Nail psoriasis is another condition that can cause nail pitting, and it affects up to 90% of patients with psoriasis in their lifetime 5
- Nail changes in AA and psoriasis can be associated with a reduced quality of life and impaired daily activities 2, 6, 5
- Other etiologies, such as onychomycosis or lichen planus, may coexist with or confound the diagnosis of nail pitting 4
Associated Conditions
- Alopecia areata (AA) is a common form of non-scarring alopecia characterized by acute hair loss, and nail involvement can occur in AA patients 2
- Psoriasis is a condition that can cause nail changes, including pitting, and it can have a significant adverse impact on quality of life 6, 5
- Nail changes in AA and psoriasis can be asymptomatic but sometimes cosmetically disfiguring 2, 6
Pathogenesis
- The pathogenesis of nail pitting in AA is not fully understood, but it is presumed to be due to the same lymphocytic infiltration seen in hair bulbs in individuals with AA 3
- Nail psoriasis is characterized by onychodystrophy, which includes morphological features of onycholysis, subungual hyperkeratosis, oil drop sign, pitting, splinter hemorrhages, leukonychia, and crumbling of the nails 6